1. Field Of The Invention
This invention relates to the purification of polyamines and more particularly to a method for the purification of polyamines prepared by reductive amination of a polyhydroxyl compound over a suitable metal catalyst or by cyanoethylation of a polyhydroxyl compound followed by reduction of the cyanoethyl derivative which in either case contain residual hydroxyl material. The purification is accomplished by using as treating agents oxides, hydroxides or alkoxides of silicon or elements of Group IIA, IIIA, IIB, IIIB, IVB or VB (CAS) of the Periodic Table.
Typically the purity of the product can be increased more than one percent by significantly reducing the hydroxyl content. An increase of this magnitude in the purity of the product translates into very substantial advantage in a commercial situation. In addition, products made with the higher purity polyamines yield polyamides which are lighter in color.
2. Related Art
Polyoxyalkyleneamines are conventionally prepared by the reductive amination of a polyhydroxyl compound or by cyanoethylation of a polyhydroxyl compound followed by reduction of the cyanoethyl derivative. The amination generally takes place over a transition metal catalyst.
In each process a significant quantity of residual hydroxyl-containing material remains in the product, the contamination normally being at a level greater than about 100 parts per million based on the amination product.
No art has been found relating to methods of reducing the hydroxyl-containing material in the product.